Diffuse scattering study by X-ray and neutron diffraction measurement and phonon dispersion relation

在室温下观察了有序晶体的散射强度的振荡形式。通过考虑原子热位移之间的相关效应，对观测到的散射强度进行了分析。随着原子间距离的增加，相关效应的值迅速减小。根据Debye-Waller温度因子参数和相关效应值，确定了第一、第二和第三近邻原子之间的原子间力常数。利用计算机模拟，从原子间力常数和晶体结构出发，对声子色散关系进行了粗略估计。

The oscillatory forms of the diffuse scattering intensities were observed from ordered crystals at room temperature. The observed diffuse scattering intensities were analyzed by including the correlation effects among thermal displacements of atoms. The values of correlation effects decrease rapidly with the increase of inter-atomic distances. From the parameters of Debye-Waller temperature factor and the values of correlation effects, the inter-atomic force constants among first, second and third nearest neighboring atoms were determined. A rough estimation of phonon dispersion relation was performed from the inter-atomic force constants and crystal structure using computer simulation.